What is the best course of treatment for a 38-year-old female patient with iron deficiency anemia, as evidenced by low hemoglobin and hematocrit levels, and normal red blood cell count, white blood cell count, and platelet count?

Management of Iron Deficiency Anemia in a 38-Year-Old Female

This patient requires immediate initiation of oral iron supplementation with one tablet daily of ferrous sulfate (200 mg), ferrous fumarate, or ferrous gluconate, continued for 3 months after hemoglobin normalization to replenish iron stores, along with investigation to identify the underlying cause of blood loss. 1

Diagnostic Confirmation

The laboratory findings strongly suggest iron deficiency anemia:

• Hemoglobin 11.0 g/dL (low) and hematocrit 35.5% (low) confirm anemia by WHO criteria (Hb <120 g/L in non-pregnant women) 1
• MCH 25.7 pg (low) and MCHC 31.0 g/dL (low) indicate hypochromia, a hallmark of iron deficiency 1
• MCV 82.9 fL (normal-low) suggests early iron deficiency before frank microcytosis develops 1

Critical next step: Obtain serum ferritin immediately to confirm iron deficiency before starting treatment, as ferritin <15 μg/L is diagnostic, though <30 μg/L is commonly used in the absence of inflammation 1, 2. If ferritin results will be delayed, starting iron therapy is reasonable given the strong clinical picture, as a hemoglobin rise ≥10 g/L within 2 weeks confirms iron deficiency even with equivocal iron studies 1.

Immediate Treatment Protocol

Oral Iron Supplementation (First-Line)

Start with ferrous sulfate 200 mg once daily (or ferrous fumarate/gluconate equivalent), which provides approximately 60-65 mg elemental iron 1, 2. The 2021 British Society of Gastroenterology guidelines prioritize once-daily dosing over the traditional three-times-daily regimen, as alternate-day or once-daily dosing improves tolerability without compromising efficacy 1.

• Take iron between meals to maximize absorption 2
• Consider adding vitamin C (ascorbic acid) to enhance absorption if response is suboptimal 1, 2
• If not tolerated: Switch to alternate-day dosing (one tablet every other day) or try a different oral iron preparation 1

Monitoring Response

• Recheck hemoglobin at 4 weeks: Expected rise is ≥10 g/L (1 g/dL) or hematocrit increase ≥3% 1, 2
• Continue iron for 3 months after hemoglobin normalizes to replenish body iron stores 1
• Monitor hemoglobin every 3 months for the first year, then annually 1

Investigation for Underlying Cause

As a 38-year-old premenopausal woman, menstrual blood loss is the most likely cause (occurring in 5-10% of menstruating women), particularly menorrhagia, though pregnancy and breastfeeding should also be considered 1. However, investigation is still warranted:

Essential Initial Workup

• Detailed menstrual history: Quantify blood loss (pictorial blood loss assessment charts have 80% sensitivity/specificity for menorrhagia) 1
• Urinalysis or urine microscopy: Exclude urinary tract blood loss 1
• Celiac disease screening: Obtain tissue transglutaminase antibodies (anti-TTG) with total IgA level, as celiac disease is found in 3-5% of IDA cases 1

Gastrointestinal Investigation Threshold

The 2021 BSG guidelines recommend a stratified approach based on age:

• Age <45 years with heavy menstrual bleeding and no GI symptoms: Celiac screening and gynecologic evaluation are sufficient initially 1
• Age ≥45 years OR presence of GI symptoms at any age: Proceed with bidirectional endoscopy (gastroscopy with duodenal biopsies and colonoscopy) to exclude GI malignancy and other pathology 1

Common pitfall: Do not delay iron supplementation while awaiting investigations unless colonoscopy is imminent, as treatment does not interfere with diagnostic workup 1.

Treatment Failure Protocol

If hemoglobin fails to rise ≥10 g/L after 4 weeks of compliant oral iron therapy 1, 2:

1. Verify compliance and absorption: Confirm patient is taking iron correctly (between meals, not with tea/coffee/calcium)
2. Reassess diagnosis: Check serum ferritin, transferrin saturation, and consider other causes (thalassemia trait, anemia of chronic disease, combined deficiencies) 2
3. Evaluate for ongoing blood loss: Particularly occult GI bleeding 1
4. Consider parenteral iron: Indicated for oral intolerance, malabsorption, or ongoing blood loss exceeding oral replacement capacity 1, 3

Parenteral Iron Indications

Intravenous iron should be considered when:

• Intolerance to at least two different oral iron preparations 1
• Malabsorption conditions (celiac disease, inflammatory bowel disease, post-bariatric surgery) 3
• Ongoing blood loss exceeding oral replacement capacity 3, 4
• Severe anemia requiring rapid correction 3

Dosing (if needed): Iron sucrose 200 mg IV over 15 minutes on 5 occasions over 14 days for non-dialysis patients 5

Special Considerations for This Patient

• Vitamin D level 25 ng/mL: This is at the lower end of normal (30-100 ng/mL range) and may warrant supplementation, though this does not directly cause anemia [@general medical knowledge@]
• Normal RDW (14.5%): Suggests uniform red cell population, consistent with early or treated iron deficiency rather than mixed deficiency states 6
• Slightly elevated eosinophils (6.5%): Consider parasitic infection as a potential cause of GI blood loss if other investigations are negative [@general medical knowledge@]

Critical Pitfalls to Avoid

• Stopping iron too early: Failure to continue for 3 months after hemoglobin normalization leads to recurrence in up to 30% of patients 1
• Missing GI malignancy: Even in premenopausal women, persistent or recurrent IDA despite adequate menstrual explanation warrants GI investigation 1
• Relying on hemoglobin alone: Normal hemoglobin with low ferritin indicates iron depletion requiring treatment before anemia develops 6
• Unnecessary blood transfusion: Reserve for hemodynamic instability or severe symptomatic anemia (Hb <7 g/dL); this patient does not meet criteria 1, 2